rLATYCRINID.E. PLATYCRINITES. 19 



work, no opinion can be formed, as we have in vain searched our own cabinets and 

 those of our friends, as well as the various museums accessible to us, without bemg 

 fortunate enough to discover the least indication of the species. 



The columnar joint wliich Mr. Phillips represents as that of a Plati/criniis, in the 

 Pala?ozoic Fossils, PI. 58, Jiff. 39, is probably not of that genus, of which there is as yet 

 no clear evidence to prove that it occurs in the Devonian Rocks. 



We are also of opinion that the P. depressus, and P. ventricosus, of Goldfuss, and 

 which he represents witli tripartite dorso-central plates, do not in reality appertain to the 

 genus Plati/crinites ; nor is the figure given by that author, of the fragment which he 

 terms P. ruffosus, at all satisfactory evidence of its identity. Neither is the columnar 

 joint which Goldfuss refers to the P. Icevis, sufficiently specific in character to warrant 

 the conclusion that it appertains to that species. 



On a careful examination of some interesting specimens of Crinoidea from Newton 

 Bushel, which Mr. Robert Alfred Austen has with great liberality and kindness placed 

 in our hands, we are fully convinced that the so called Platycrinites found in the 

 Devonian Rocks, do not belong to that genus. The P. inter scapularis, (PhilUps) for 

 instance, and others with tripartite dorso-central j)lates, offer such decided characters 

 that we are of opinion they should be removed from the Platycrinites and arranged in 

 a new genus, for which we propose the name of Hexacrinites. 



The true Platycrinites have an undi\-ided dorso-central plate as observed at page 6. 

 And it is probable that the genus is not found in any formation of greater antiquity 

 than the carboniferous limestone. 



2. Species. Platycrinites spinosus. (Austin.) 



Definition. — Visceral bulb globose, Dorso-central plate entire and pentagonal. Pe- 

 risomic plates, (costals,) five ; Main rays five, subdivisions twenty, tentaculated to their 

 extreme pomts. Abdominal plates hexagonal, each of which is lengthened in the 

 centre into a spiny process. Oral tube much elongated, and its upper portion 

 studded with thorn Uke projections. Column cfrcular at its attachment to the body, 

 but gradually becoming elliptical as it recedes from it. Base of attachment unas- 

 certained. 



Synonymes and References. 



Platycrinites Spinosus. — Messrs. Austin, Ann. Sg Mag. Nat. Hist. No. 63, page 109, 

 and No. 69, p. 199. 



